I just heard one new feature of the Nintendo Switch controller was a "share" button, prompting much eye-rolling on my part. I've never used that button on my PS4 controller, except one time I think by accident.

This is one of the most-used features on my Xbox One. It allows me to record clips of my gameplay footage so I can show off to my friends! My friends all heavily use this feature as well. It's entertaining to look at other players' high scores, tricks or glitches and try to accomplish similar things in your own game.

From my experience with the PS4, the share button on that console has the same basic functionality. Give it a try next time you beat a really hard level or get a high score!

I don't have a share button on any of my consoles, but I do use Miiverse pretty regularly, so I can't say I wouldn't use this if I ever got a Nintendo Switch. In Mario Kart 8, there was an option to share short clips to Youtube or to Miverse. Given Nintendo's move into mobile, I'd expect Miiverse to be the primary share option, with some very Nintendo way to tie it to Facebook or Youtube as a secondary option (i.e. share only editied, shortened, or score based stuff to Facebook or Youtube), and probably some kind of Miitomo integration.

I sometimes use the Share button on my PS4 controller to post entertaining pictures or videos of my games on Facebook (not that anyone gives feedback on them, but I digress). It's a nice, convenient way to record footage for various purposes without having to set up a separate device to do so. I just hope the Switch follows the PS4 model of recording footage and not the Xbox One's. For some reason, doing this exact same thing on the Xbox One is considerably less intuitive and takes a hell of a lot longer to do properly than on PS4.